Temporal risk assessment – 20th century Pb emissions to air and exposure via inhalation in the Swedish glass district

Abstract

The objective of the present study was to assess historical emissions of Pb to air around a number of glassworks sites in southeastern Sweden, and the possible implications for human exposure. To do so, a four-step method was applied. First, emissions of Pb to air around 10 glassworks were modelled for the 20th century. Second, an assessment of the resulting exposure was made for a number of scenarios. Third, the number of people potentially exposed at different times was estimated, and fourth, measurements of “current” Pb concentrations in PM10 material from four sites were conducted in 2019. The results show that the highest emissions, and exposures, occurred from 1970 to1980. It coincides with the time period when the highest number of people resided in the villages. At this time, the average Pb concentration in air around the six largest factories was about 2.4 μg Pb/m3, i.e. 16 times the present US national ambient air quality standard (NAAQS) of 0.15 μg Pb/m3. By year 2000 the modelled average concentration had dropped to 0.05 μg Pb/m3, a level that is normal for urban regions today. The PM10 measurements from 2019 indicate a further decline, now with a mean value of about 0.02 μg Pb/m3. Over the entire study period, inhalation hazard quotients (HQs) exceeded the dietary HQ by many orders of magnitude, indicating that inhalation has been the most prevalent exposure pathway in the past. At present, both pathways are judged to be associated with low exposures. Even if only roughly approximated, a picture of the historical exposure can increase our understanding of the connection between exposure and disease, and can be valuable when risks are to be communicated to residents near contaminated areas.